A storage tank may be disposed on a downstream side of a condenser in a working fluid conduit of a working fluid cycle, such as a refrigeration cycle or a Rankine cycle, of a waste heat recovery system, and a liquid phase working fluid condensed by the condenser may be stored in the storage tank. A pump for circulating a fluid may be disposed on a downstream side of the storage tank.
The condenser, the storage tank, and the pump may be installed in a section where the liquid phase fluid is present, the condenser may be disposed above the storage tank, and the storage pump may be disposed above the pump. That is, a pressure loss may be reduced by disposing the condenser, the storage tank and the pump along a gravitational, or vertical, direction, and the liquid phase working fluid may be collected in the storage tank due to the weight thereof even when the working fluid cycle is stopped.
The storage capacity of the storage tank has to be considered based on the arrangement and capacity of the heat exchanger (an evaporator, a boiler and a condenser) of the working fluid cycle. Further, the storage capacity of the storage tank may be set in consideration of the amount of fluid filled in the condenser and the conduit when the cycle is operated and of a basic capacity for circulation of the cycle.
The working fluid may be present only in a liquid phase in a portion of the whole section of the working fluid cycle, but the phase of the working fluid may be changed based on the operation of the working fluid cycle at the remaining portions of the working fluid cycle. For example, the working fluid may be present in a liquid phase in an air boiler or a recuperator of a Rankine cycle of a waste heat recovery system, and may be present in a combination of a liquid phase and a vapor phase in an EGR gas boiler, an exhaust gas boiler or a pipe.
Accordingly, the storage capacity of the storage tank may be a value obtained by adding the fixed capacity of the working fluid that is always present in a liquid phase and a variable capacity of the working fluid varied, or present, through a phase change.
However, because the percentage of the fixed capacity in the storage tank is very large, the volume of the storage tank has to be larger regardless of an operational state of the working fluid cycle. Accordingly, a required installation space of the working fluid cycle may be large.
Further, because the storage tank has to be designed as a pressure-resistant container based on the type of the working fluid, the weight of the storage tank may become excessive.